Flame-retardant composition

ABSTRACT

A composition which when applied to textile fabrics imparts flame retardancy. The composition is a combination of an aziridinyl phosphine oxide or sulfide and a phosphoric amide.

United States Patent Linderman et a1.

[ Feb.8, 1972 [54] FLAME-RETARDANT COMPOSITION [72] Inventors: Roger C. Linderman; Charles D. Cline,

both of Charlotte, NC.

[52] US. Cl. ..252/8.1, 117/136, 117/143 R, C09d/5/ 18 [51] Int. Cl. "C09k 3/28 [58] FieldolSearch ..117/136, 143 R; 252/8.1; 106/15 FP; 260/239 EP, 2 P; 8/1 16.2

[56] References Cited UNITED STATES PATENTS 2,891,877 6/1959 Chance et a1. ..117/136 2,901,444 15/1959 Chance et al. 17/136 X 2,906,592 9/1959 Reeves et a1. 17/1 36 X 2,911,325 11/1959 Drake et a1. ..117/136 3,034,919 5/1962 Steinhaver 7.1 17/137 3,516,853 6/1970 Tesoro etal ..117/136 FOREIGN PATENTS OR APPLICATIONS 770,789 3/1957 Great Britain ..117/138 1,575,975 7/1969 France ..1 17/136 OTHER PUBLICATIONS Drake et al. A pplicutiun of The Apo-Thpc F lame Retardant to Cotton F abirc, Amer Dyestufj" Reporter, Vol. 50, No. 4, pp. 27-32 Feb. 20, 1961 Primary ExaminerWilliam D. Martin Assistant Examiner1-larry J. Gwinnell Attorney-Frank E. Robbins, Joseph Shekleton, Janet E. Price, Robert D. Weist, Martha A. Michaels and Dorothy R. Thumler ABSTRACT A composition which when applied to textile fabrics imparts flame retardancy. The composition is a combination of an aziridinyl phosphine oxide or sulfide and a phosphoric amide.

10 Claims, No Drawings FLAME-RETARDANT COMPOSITION The invention of this application is as indicated a flame retardant composition. When applied to textile fabrics it is effective to render those fabrics resistant to burning. The invention is particularly applicable to cellulosic fabrics.

Many fire-retardant compositions have in the past been applied to textile fabrics which then intumesce or form a cellular char when exposed to a direct flame or high temperatures.

Many of these compositions are water-soluble and treated fabrics produced from such composition, while satisfactory for limited purposes, have proven to be somewhat unsatisfactory when they are subjected to frequent washings or conditions of high humidity, because the water-soluble materials are leached out of the fabric under such conditions and the fabric loses its fire-retardant properties. ln efforts to avoid these shortcomings, thennosetting resins such as ureaformaldehyde resins have been used to give some permanency to the fire-retardant treatment and thus protect the substrate as well as provide an ornamental finish thereon. These therrnosetting resins, however, have the disadvantage of becoming brittle when they are highly polymerized with the result that the treated fabric is stiff and has reduced resistance to abrasion; furthermore, the flame-retardance is not satisfactory.

Other fire retardant compositions have not been entirely satisfactory because the amount of add-on" required to provide the desired degree of flame retardancy is very high, i.e., in some cases as much as 30 or 40 percent of the fire-retardant composition based on fabric weight must be incorporated into the fabric to render the fabric fire-retardant. This makes the process costly, of course, and also it usually give the fabric a poor hand.

The desirability of rendering textile fabrics resistant to fire and burning is evident. Bedding, upholstery and drapery fabrics are of particular interest in this regard, but the advantages of fireproofing wearing apparel likewise are manifest. Fireproof night wear, for example, represents a very desirable goal. Many fires, in the home or in public gathering places, begin with an unnoticed burning cigarette which ignites bedding, curtains, or drapes which in turn spread the fire to other more difficulty bumable materials such as wood. The use of fire-retardant fabrics in these instances undoubtedly would diminish the number of serious fires very significantly, because the fire would burn out before it has a chance to reach serious proportions.

In accordance with the tenninology which has been developed in this field fire-retardancy results from the treatment of a substrate such as a textile fabric with various chemicals so that it becomes resistant to the propagation of flame across its surface after the igniting flame has been removed; that is, a fire-retardant material will not support combustion independently of an external source of heat. In contact with an open flame, however, or at elevated temperatures, fire-retardant cellulosic material can be expected to char and decompose.

The treated textile fabrics of the present invention have a high degree of fire-retardancy while at the same time retaining to a large extent the original hand of the untreated textile fabrics. The color, physical appearance, strength and softness of the fabric are not substantially affected by such treatment.

It is accordingly a principal object of the present invention to provide fire-retardant compositions.

It is a further object of the present invention to provide fireretardant compositions which are effective at relatively low add-on concentrations.

it is a further object of the present invention to provide fireretardant fabrics.

it is a further object of the present invention to provide fireretardant fabrics which retain their fire-retardancy after repeated launderings and dry cleanings.

It is a further object of the present invention to provide fireretardant fabrics which have a good hand.

It is a further object of the present invention to provide fireretardant fabrics which are strong and resistant to abrasion.

It is a further object of the present invention to provide a process for imparting fire-retardancy to new fabrics.

These and other objects are accomplished by a fire-retardant composition comprising an aziridinyl phosphine oxide or sulfide and a phosphoric amide. These ingredients are soluble or readily dispersible in water and they are ordinarily applied to a fabric from an aqueous solution. A fabric thus treated is characterized by a high degree of flame resistance.

The phosphoric amide may be any of several such compounds conforming to the structure:

where R is a lower alkyl group or hydrogen, A is NH NHR or R0, B is NH NHR or R0, and X is oxygen or sulfur. Specific illustrations of suitable phosphoric amides include phosphoric triamide, thiophosphoric amide, methyl phosphoric diamide, ethyl thiophosphoric diamide, diethyl phosphoramide and the N-methyl, N-ethyl etc., analogs thereof. The lower alkyl group may contain up to four carbon atoms, i.e., it may be methyl, ethyl, propyl or butyl.

Phosphoric triamide is preferred. It may be prepared by the reaction of anhydrous ammonia with phosphorous oxychloride in an inert solvent such as chloroform. The stoichiometry of the reaction involves one mol of phosphoric oxychloride and 6 mols of ammonia. The product mixture includes not only the desired phosphoric triamide, but also ammonium chloride. The ammonium chloride may be removed by reaction with diethylamine to form diethylamine hydrochloride and ammonia. The ammonia evolves from the product mixture and the diethylamine hydrochloride may be removed by washing with chlorofonn. The reaction is illustrated by the following equation:

The phosphoryl triamide is a white solid, soluble in cold water.

The aziridinyl phosphine oxide or sulfide usually is prepared by reaction of phosphorous oxychloride or thiophosphoryl chloride with an alkyleneimine such as ethyleneimine. This reaction illustrated, reaction is the preparation of tn's-aziridinyl phosphine oxide, by the following equation:

The above equation shows the fonnation of tris-aziridinyl phosphine oxide, which is preferred for the purposes of this invention, but mono-aziridinyl and di-aziridinyl phosphine oxides as well as the mono-, diand tris-aziridinyl sulfides likewise are contemplated for these purposes. Propyleneimine and other lower (up to four carbon atoms) alkyleneimines may be used instead of ethyleneimine in the preparation of this ingredient.

As indicated, the ingredients of the fire-retardant compositions ordinarily are soluble in water and are applied to textile fabrics from an aqueous solution. Where one or both of the ingredients are not readily soluble in water a small proportion of dioxane or similar water miscible, inert solvent may be added to solubilize these ingredients in the aqueous solution. The relative proportions of ingredients which may be used are from about I to about 10 parts (molar) of aziridinyl phosphine oxide or sulfide and from about I to about 10 parts (molar) of phosphoric amide. Preferably, the aqueous solution will contain from about 2 to about 4 parts, on a molar basis, of phosphoric amide per part of aziridinyl phosphine oxide or sulfide.

The above aqueous solution may also contain a latent acid cataiyst such as zinc chloride, zinc nitrate or magnesiumchloride which serves to promote the reaction of the phosphoric amide and aziridinyl phosphine oxide or sulfide with each other and with the textile fabric during the curing step. Residual ammonium chloride from the phosphoric amide product mixture will also serve such purpose. The catalyst, when used, should be present in a concentration of from about 0.1 to 10 percent based on the weight of the fire retardant solution. The temperature of the treating both is conveniently within the range of from about 10 C. to about 35 C.

The flame-retardant compositions herein are preferably applied to a fabric by immersing the fabric in an aqueous solution of from about 1 percent to about 30 percent by weight of the flame-retardant composition, then passing it through a squeeze roller. Multiple immersions and/or squeezings can be effected if necessary to achieve the desired application on the fabric. Ordinarily, from about 50 percent to about 100 percent by weight of flame-retardant solution based on the weight of the fabric is thus applied. The fabric is then dried at elevated temperature, i.e., from about 75 C. to about 125 C., then cured by heating at a temperature within the range of from about 125 C. to about 250 C. The time of curing will vary depending upon the temperature, i.e., less time is required to cure at 250 C., than is required to cure at 125 C. After the curing step, the amount of dry flame-retardant composition deposited on the fabric is from about 5 percent to about 25 percent by weight of the fabric. Other methods of applying the flame-retardant composition to the fabric may be employed, e.g., spraying, brushing on, sprinkling, etc.

If desired, softening agents may be introduced into the flame-retardant solution, or alternatively, any softening step may be postponed until after the treated fabric has been cured. The softening step results in a softer, more desirable hand. The softening agent may be applied by any of the conventional techniques. Suitable textile softening agents include polyethylene emulsion, ethylene glycol distearate and the like. The concentration of the softening agent ordinarily is from about 0.2 percent to about 5 percent.

The invention is illustrated by the following examples which are not to be taken as limiting in any respect. All parts and percentages are by weight unless otherwise expressly stated.

EXAMPLE I An 80-square cotton cloth is immersed in an aqueous solution of 9 percent (0.05 molar part) of tris-aziridinyl phosphine oxide and 12 percent (0.13 molar part) of phosphoric triamide, then passed between rubber squeeze rollers to a dripdry state. The quantity of aqueous solution thus imparted to the cotton fabric is 70 percent based on the weight of the fabric. The fabric is dried at 105 C. and cured for 2 minutes at 160 C. After washing (to remove excess flame-retardant ingredients) and drying, the treated fabric shows a percent weight increase and a char length of 2.5 inches, determined in accordance with the AATCC Test method No. 34-1969. This test is carried out as follows:

A test sample of the fabric, 2%X10 in., is placed in the flame of a Bunsen burner for 12.0 seconds, then withdrawn and allowed to glow and smolder until it extinguishes itself. The sample then is torn under standard conditions, through the charred area and the length of the tear is taken as a measure of fire-retardance, i.e., the less the length of tear the more fireretardant is the sample. A sample fabric with relatively poor flame-retardancy will burn along its entire length and be rated BEL (burn entire length).

After full-cycle launderings at 140 F. in a home-type washing machine, the treated fabric of this exampled showed a char length of 3.5 inches, indicating that the flame-retardant composition is sufficiently attached to the fabric that it does not wash out on laundering.

EXAMPLE ll An -square cotton fabric is immersed in an aqueous solution of 7 percent (0.04 molar part) of tris-aziridinyl phosphine oxide and 12 percent (0.13 molar part) of phosphoric triamide, then passed through rubber squeeze rollers to a dripdry state. The increase in weight of the cotton fabric is 70 percent. The fabric is then dried at C. and cured for 2 minutes at C. After washing (to remove excess flame-retardant ingredients) and drying, the treated fabric shows a 10 percent weight increase and a char length of 2.5 inches. measured in accordance with the above AATCC test.

EXAMPLE Ill Char length After 5 25 Percent appliwashwash- Type of fabric add-on cation ings ings Broadcloth (cotton) 13. 3 4% 8 5 Poplin (cotton) 11. 8 4% 6 4 Corduroy (cotton). 13. 5 4 4% 4% Sateen (cotton) 12.8 4 4 6% Worsted/cotton 11. 8 6% 6% BEL l Flannel (cotton) 13. 3 4 4 6 4% Burned entire length.

Other properties of a fabric are of course affected by the treatment herein. Wrinkle recovery, for example, is improved. Results of AATCC Test 16-1968 showed an increase in recovery angle for each of the treated cotton fabrics in the above table. Tear strength (determined by the Elmendorf Tear Test) and tensile strength (determined by ASTM Test D3949) are diminished somewhat, but to a much lesser degree than treatment with conventional durable press finishes.

The flame-retardant compositions of this invention are effective on a variety of fabrics and especially so on cellulosic fabrics. Cotton and rayon are benefitted most by the application of these materials, and fabrics of mixed content having at least about 65 percent of a cellulosic material, e.g., cotton or viscose rayon, are also very much improved.

A notable feature of the invention herein is the effectiveness of treatment at low add-on concentration. At a level of 10-12 percent add-on the flame-retardant compositions of this invention are superior to those of the prior art at much higher levels of add-on. A typical prior art flame-retardant composition, for example, when used at 27 percent add-on showed a char length of 2% inches, but after five launderings it was rated BEL.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention, following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention and the limits of the appended claims.

We claim:

l. A fire-retardant composition efiective at low add-on and characterized by relative stability to laundering, comprising in combination from about 1 to about molar parts of an aziridinyl phosphine oxide or sulfide and from about 1 to about 10 molar parts of phosphoric triamide.

2. The fire-retardant composition of claim 1 wherein the aziridinyl phosphine oxide or sulfide is a tris-aziridinyl phosphine oxide.

3. The fire-retardant composition of claim 2 wherein the tris'aziridinyl phosphine oxide conforms to the structural formula:

UH -CH 6. An aqueous fire-retardant composition effective at low add-on and characterized by relative stability to laundering, comprising from about I to about 10 molar parts of an aziridinyl phosphine oxide or sulfide and from about I to about [0 molar parts of phosphoric triamide.

7. The aqueous fire-retardant composition of claim 6 wherein the relative proportion of ingredients is within the range of from about 2 to about 4 molar parts of phosphoric triamide per molar part of an aziridinyl phosphine oxide or sulfide.

8. The aqueous fire-retardant composition of claim 6 wherein the combination of aziridinyl phosphine oxide or sulfide and phosphoric triamide is present in a concentration of from about 1 percent to about 30 percent by weight.

9. The aqueous fire-retardant composition of claim 6 wherein the aziridinyl phosphine oxide or sulfide is a trisaziridinyl phosphine oxide.

10. The aqueous fire-retardant composition of claim 9 wherein the tris-aziridinyl phosphine oxide conforms to the structural formula:

CHr-CH:

CH1 N 

2. The fire-retardant composition of claim 1 wherein the aziridinyl phosphine oxide or sulfide is a tris-aziridinyl phosphine oxide.
 3. The fire-retardant composition of claim 2 wherein the tris-aziridinyl phosphine oxide conforms to the structural formula:
 4. The fire-retardant composition of claim 1 wherein the aziridinyl phosphine oxide or sulfide is a tris-aziridinyl sulfide.
 5. The fire-retardant composition of claim 4 wherein the tris-aziridinyl sulfide conforms to the structural formula:
 6. An aqueous fire-retardant composition effective at low add-on and characterized by relative stability to laundering, comprising from about 1 to about 10 molar parts of an aziridinyl phosphine oxide or sulfide and from about 1 to about 10 molar parts of phosphoric triamide.
 7. The aqueous fire-retardant composition of claim 6 wherein the relative proportion of ingredients is within the range of from about 2 to about 4 molar parts of phosphoric triamide per molar part of an aziridinyl phosphine oxide or sulfide.
 8. The aqueous fire-retardant composition of claim 6 wherein the combination of aziridinyl phosphine oxide or sulfide and phosphoric triamide is present in a concentration of from about 1 percent to about 30 percent by weight.
 9. The aqueous fire-retardant composition of claim 6 wherein the aziridinyl phosphine oxide or sulfide is a tris-aziridinyl phosphine oxide.
 10. The aqueous fire-retardant composition of claim 9 wherein the tris-aziridinyl phosphine oxide conforms to the structural formula: 